1. Field
The disclosure relates to a fixing apparatus for an image forming apparatus. More particularly, the disclosure relates to a belt type fixing apparatus and an image forming apparatus having the same.
2. Description of the Related Art
Generally, an electrophotographic image forming apparatus such as a laser printer forms a developer image corresponding to print data on a printing medium, and uses a fixing apparatus to permanently fix the developer image on the printing medium by applying predetermined heat and pressure to the developer image.
The fixing apparatus may include a pair of rollers, that is, a heating roller that generates a predetermined heat to be applied to the printing medium and a fixing roller that applies a predetermined pressure to the printing medium.
In recent years, in image forming apparatuses capable of high-speed printing, a belt type fixing apparatus using a fixing belt, which is an endless belt, is widely used instead of the heating roller.
As illustrated in FIG. 1, a conventional belt type fixing apparatus guides the rotation of a fixing belt 210 by using guide bushes 200 provided at the opposite ends of the fixing belt 210. A first surface 201 of the guide bush 200 restricts an axial movement of the fixing belt 210, and a second surface 203 of the guide bush 200 supports the rotation of the fixing belt 210 inside the fixing belt 210. The first surface 201 and the second surface 203 of the guide bush 200 are formed to be perpendicular to each other.
At this time, at a connecting portion 205 between the first surface 201 and the second surface 203 of the guide bush 200 forming the right angle, there exists a tool shape (or tool trace) which is generated when the guide bush 200 is machined. For example, as illustrated in FIG. 2, a round having a predetermined curvature is formed at the connecting portion 205 between the first surface 201 and the second surface 203 of the guide bush 200.
While the fixing belt 210 rotates, the fixing belt 210 receives an axial force B. Then, as illustrated in FIG. 3, the fixing belt 210 is moved in the axial direction along the second surface 203 by the axial force B, so that one end 210a of the fixing belt 210 climbs up along the round shape 205 formed between the first surface 201 and the second surface 203. Then, the one end 210a of the fixing belt 210 receives a force that acts from the inside of the fixing belt 210 to the outside to cause the one end 210a of the fixing belt 210 to be spread out. Accordingly, when the fixing belt 210 repeatedly rotates along the guide bush 200, the one end 210a of the fixing belt 210 is cracked and broken.
Accordingly, the development of a belt type fixing apparatus capable of suppressing fatigue cracks at opposite ends of the fixing belt 210 has been demanded.